15-inch, Mid 2009 2.66 ghz intel core 2 duo macbook pro 4 GB 1067 MHz DDR3 I bought one of these a couple of weeks ago. The most important operation I had in mind was to fit my 500GB drive from my old Macbook in here as a second drive. I backed up all the files on an external drive, then fitted it into a caddy, which I then installed. Seemingly there were no issues, other than the fact I struggled to fit in one of the three screws which fit the caddy in place where the Superdrive had previously had been. After many attempts, which saw the caddy's hole widening with each failed attempt, I took the risk of resealing the lid and powering up. The drive was detected no problem. After a few days, after a restart my second HD's icon did not immediately appear on the desktop. I ran Disk Utility, but my second HD was greyed out. After a while, the icon reappeared and I opened iTunes - the second drive contains all my Library - and everything opened as normal. After another restart, the second HD icon again took longer than expected to appear on the desktop. Opening iTunes again, I got this message: "The folder iTunes is on a locked disk or you do not have write permissions for this folder". In Disk Utility, I got the message "OS X can't repair the disk "Macintosh HD 2.0. You can still open or copy files on the disk, but you can't save changes to files on the disk. Back up the disk and reformat it as soon as you can." I restarted the Macbook and the same happened, except in Disk Utility, the second HD was no longer grayed out. I can see the second HD on the desktop and can browse it in finder. However, iTunes is still giving me the above message and then asks me to choose a folder again. Now, is this likely to be a fault of the caddy - which did look secure enough when I tried to install it properly - missing that third screw? It was a nightmare to even try and get it in. I'm very concerned about this - all I want is my second, larger HD working internally every single time I boot up. If anyone can offer any assistance, it would be much appreciated.